Brake



June '23, 1942- J. CARNES BRAKE Filed Sept. 27, 1941 4 Sheets-Sheet 1 dannes I Cannes June 23, 1942. J. J. CARNES 2,287,023

' BRAKE 2 Filed Sept. 27, 1941 4 Sheets-Sheet 2 Fig.4.

145;, 3" Riga-'15 29 5; w I 51 '3 I A v I C e Z I a gwucwto'b June 23,1942.

J. J.= CAIVQNES 2,287,023

BRAKE Filed Sept. 27, 1941 I 4 Sheets-Sheet 4 Fig.8.

gwva/Mov James Carnes Patented June 23, 1942 BRAKE James J. Carnes,United States Army Application September 27, 1941, Serial No. 412,582

(Granted under the act of March 3, 1883, as amended April 30, 1928; 3700. G. 757) Claims.

The invention described herein may be manufactured and used by or forthe Government for I governmental purposes, without the payment to otherof the servo-action type, where the pri-" mary shoe is not anchored andpresses against the secondary shoe, as illustrated by Patent No.

2,101,425, granted to L. C. Brisson December 7,

1937. In the first case, the primary shoe is selfenergizing and doesmost of the braking. When the drum revolves in the reverse direction thesecondary shoe is self-energizing and does most of the braking. While itis important to have good brakes both when the vehicle is going forwardand in reverse, this type brake is open to the disadvantage, in view ofthe fact that the the greater portion of use of the brakes is while thevehicle is in forward motion, that the lining of' the primary shoe wearsout first. In the servo-action type of brake the greater pressure istransferred to the secondary shoe and therefore the secondary shoelining wears out before the primary shoe lining. A further disadvantageof the servo-action type brake is the fact that unless the shoes are inapproximately exact adjustment, the brakes will grab or lock the wheels,

due to the fact that both shoes run with the drum.

It is the primary object of this invention to combine in a single brakemechanism the advantages of the two types of brakes mentioned above andat the same time to provide a brake mechanism which will overcome thedisadvantages inherent in either type.

It is an object of this invention to provide a brake mechanism in whicheach of the brake shoes of the mechanism does the same amount of workwhether the vehicle is moving forwardly or backwardly.

A further object of my invention is to provide an improved brakemechanism of relatively simple and inexpensive construction which willafford a positive control and a smooth and efficient action duringbraking.

Other objects and advantages of my invention when taken in conjunctionwiththe accompanying drawings in which Fig. 1 is a view in elevation ofone of the preferred embodiments of my invention;

Fig. 2 is a diagrammatic view of Fig. 1 showing the relative movement ofthe elements of Fig. 1;

Fig. 3 is a fragmentary view of an embodiment of the invention using asingle link to connect the two shoes;

Fig. 4 is an elevation of an embodiment of the invention adapted for usein small brakes;

Fig. 5 is a view in elevation of another embodiment of the invention andadapted for use in brakes operated either hydraulically or mechanicallyiI Fig. 6 is a view in elevation of an embodiment of the invention inwhich the link mechanism is connected between the toes of the brakeshoes;

Fig. 7 is a view in elevation of a modified form of link mechanismconnecting the toes of the brake shoes, and

Fig. 8 is a second modification of the link mechanism shown in Fig. 6,in which an adjustable connecting arm is placed in the linkage system.

I have illustrated my invention as applied to a hydraulic brake adaptedto brake a rotating element of a machine, as, for example, the wheel ofan' automotive vehicle; but it is to be understood that my invention isin no way limited in its use to this particular adaptation. Throughoutthe drawings the elements are shown in the position they assume afterthe brakes are aplied.

p In Fig. 1, l represents a brake drum which is intended to be rigidlyfixed to the rotating machine part to be braked; 5 represents a backingelement which is intended to be rigidly fixed to the nonrotating part ofthe machine. The normal direction of rotation of the drum l is indicatedby the arrow hence, in the case of an automotive vehicle, said arrow findicates the direction of rotation of the drum corresponding to forwardmotion of the vehicle.

Mounted within the drum I is a primary brake shoe 2 and a secondarybrake shoe 3 each having on their contact side a suitable friction limng4. v The backing plate 5 carries fixedly upon it a brake actuating means9, adjustable anchor pins 8 and I, guide pins II and I2, and anadjustable eccentric l3. The adjustable anchor pins 8 and I are ofconventional design such as is shown in United States" Letters PatentNo.

will be apparent from the following description 2,161,640, granted June6, 1939, to S. Schnell.

The brake actuating means 9 may be any suitable wheel cylinder of ahydraulic brake system and is here represented as a two-way actingcylinder. The primary brake shoe 2 is mounted for limited rotation aboutthe adjustable anchor pin 1 adjacent the end of the shoe remote from theactuating means. The amount of rotation and its path are limited by theguide pin l2. The other end of the primary shoe 2 is attached by meansof an adjustable link l4 to an .operating arm of the actuating means 9.The secondary brake shoe 3 is attached at one end by means of anadjustable link IE to a second operating arm of the actuating means 9.As will be described later this link l5 acts as an anchor pin for thesecondary shoe 3 about which the shoe may have a limited rotation. Theamount of rotation of the shoe 3 and its path are determined by guidepin H. Connecting primary shoe 3 are actuating links 8 (only one shown).The links 8 are mounted on an adjustable anchor pin 6 so as to be freeto rock about the pin. The ends of links 8 are attached to the shoes 2and 3 by means of link pins l8 and 24 respectively. The pins In and 24are fixed to the ends of links 8 and are adapted to be engaged byslotsin the ends of shoes 2 and 3 respectively. The adjustable eccentric I3is provided to coact with brake shoe 2 in order to adjust the brakeforthe shoes to their inoperative position. An added spring I! isattached between the backing plate 5 and secondary shoe 3. The purposeof spring I! is to place a greater retractive. force upon secondary shoe3 so that when the wheel cylinder 9 is operated shoe 3 will be heldagainst link l5 and caused o rotate about link 15 as an axis.

The operation of the embodiment of my invention shown in Fig. 1 will beclear by a consideration of Fig. 2, a schematic diagram showing themovement of the elements of a brake constructed according. to theinvention. As the force is applied from the actuating means 9 to theupper portion of primary 'shoe 2, the upper portion of said shoe will begiven an outward rotation about anchor pin 1 as an axis in the directionshown by arrow a, forcing the lining 4 of primary shoe 2 into contactwith drum I. At the same time the other end of said shoe will be givenan inward rotation about anchor pin 1 as an axis in the direction shownby arrow b. This in turn will impart an inwarl -;otation of the endsoflinks 8 attached to link pin in about the anchor pin 6 as an axis in thedirection shown by arrow 0. The other ends-of the links 8 will thus be.given an outward rotation about anchor pin 8 as an axisflin thedirection shown by'arrow d. This motion of pin 24 imparts to secondaryshoe 3 an outward rotation about anchor pin 15 as an axis in thedirection shown remain substantially at rest due to the fact that springI I is of suflicient strength to overcome the pressure produced by theactuating means 9. It'will be seen-that, as a result of the method ofanchoring the brake shoes, while the vehicle is in forward motion thetoe of both the primary and secondary shoes will be rotated in the s mesense as the direction of rotation of the drum I. This will effectivelycause both shoes to be self energizing. Thus the braking effort of bothshoes .will be substantially equal and they willeach b subjected toequal amounts of wear. The advantages of the invention are equallypresent when the vehicle is in reverse since any tendency of either ofthe brake shoes to assume more than its share of the braking load isinstantly transferred to the other of said shoes through the linkmechanism.

Fig. 3 shows an alternate link mechanismwherein a singlelink 23 may besubstituted for the pair of links 8 shown in Fig. 1. a solid link 23 isprovided with cam ends l8 and 2| adapted to engage correspondinglyshaped slots 20 and 22 in the web of the ends of shoes 2 and 3respectively. The link 23 is mounted to rotate about pin 6. Theoperation of the device is identical with the construction shown in Fig.1.

Where is it desired to use the invention in a small brake, it may bediilicult to utilize the construction shown in Fig. 1 and still havesumcient braking area. In such a case the modification shown in Fig. 4may be used. In this embodiment of the invention the heel of the primaryshoe 2 is extended in an inwardly curved manner at 2a so as to overlapthe toe of secondary shoe 3. Links 8| are pivoted about pin 6 and carrypins l8 and 24 adapted to engage the slots in shoes 2 and 3respectively. A hole 25 is placed in the extended heel of the primaryshoe 2 to allow movement of the shoe about anchor pin 6. The operationof this form of the invention is identical with the construction shownin Fig. 1.

In Fig. 5 there is shown an embodiment of the invention in which thesecondary shoe 3 is floating rather than anchored to the actuating means8. In this modification springs 26 and 21 attached to an anchor pin 28replace springs l6 and H appearing in Fig. 1 and apply equal pressure toshoes,2 and 3. The anchor pin 28, in this embodiment, merely acts as astop to hold the secondary shoe 3 in its proper retracted position.There is also shown a modified form of link 82 which has a rounded camportion 36 on one arm of the link adapted to coact with a slot in theweb of brake shoe 3 and a notched portion 31 on the other arm of thelink adapted to coact with a rounded cam 38 on the heel of brake shoe 2.The actuating means 9 causes both shoes 2 and 3 to be forced against thedrum I. The link with the drum the pressure in the wheel cylinder 9 isincreased. This increase is effective braking force without increase inapplied pressure is particularly useful in stopping heavy equipment. Insuch an arrangement whenthe brake is applied while the drum is rotatingin a direction the reverse of that shown by arrow 1, the fact that thesecondary shoe 3 is floating allows it to become, in a relative manner,self-energizing. This force is applied through the link 82 andtransmitted to the primary shoe 2 thus equalizing the pressure on thetwo shoes.

For safety it is customary to have an auxiliary mechanicaloperatingsystem for supplementing the hydraulic operating system in case offailure.

An arrangement adapted for this purpose is shown In the figure,

shoes 2 and 3 into contact with drum I.

about its anchor pin 6. to pivot about its anchor pin 39- and puts addi-2,287,023 in Fig. 5. It is obvious, however, that the arrangement couldbe applied to any of the embodiments shown in the other drawings withequal success. or could be substituted completely for the hydraulicoperating means. The system for applying the mechanical operating forceis as follows: on the web of shoes 2 and 3 adjacent their ends remotefrom link 82 are placed respectively pins 29 and 30. Rotatably mountedon pins 29 and 30 are links 33 and 34 respectively. Link 33 is attachedto the body of link 34 by means of pin 3|. Operating arm 35 is attachedto the free end of link'34 by means of pin 32. When a force is appliedin thedirection of arrow y to the arm 35, the links 34 and 33 tend torotate clockwise and counterclockwise respectively about pin 3|. Thismovement imparts an outward motion to pins 29 and 30.forcing the lining'4 of The link 82 acts as before to equalize the pressure on the .twoshoes.

A somewhat different system of links which may be used toachieve thebenefits of my invention is shown in Fig. 6. In this figure the pair oflinks 83, only .one of which is shown, instead of being connected to theheel of the pri mary shoe 2, is connected to one end of a pair of crankarms 40, only one of which is shown. The crank arm 40 is mounted topivot about a fixed anchor pin 39 fixedly'attached to the backing plate5. The other end of the crank arm is fastened to the link l4 carried byan operating arm of the actuating means 9. The construction 'of theremainder of the brake mechanism is similar to that described in Fig. 1,with the exception that the secondary shoe 3 is mounted to rotateagainst a fixed anchor pin 4| rigidly attached to the backing plate 5adjacent the operating means 9.

The operation of this form of link system is as follows: when force isapplied by the operating means 9 this force is transmitted through pin Mto the primary shoe2 causing it to'rotate outwardly about anchorpin 1forcing the lining 4 into contact with the drum I. A portion of theactuating force is transmitted to the slotted end of the crank arm 40 bymeans of pin l4 causing a counterclockwise rotation of the crank 40about its pivot pin 39. The corresponding movement of the other arm ofthe anchor 40 istransmitted to the link 83 by means of pin in impartingto said link a clockwise rotation about its pivot pin 5. Thecorrespondingmovement of the other end of the link 83 forces the toe ofthe secondary shoe 3 to have an outward rotation about anchor pin 4! asan axis, which in turn forces the lining 4 into contact with the drum I.On rearward rotationof the'brake drum the secondary shoe 3 moves awayfrom its anchor 4i slightly and in so doing forces link "to pivot Thiscauses crank 40 tional pressure on the toe of the primary shoe 2.

In Fig. '7 is shown a modification of the arrangement shown in Fig. 6 inwhich a pair of links 42, only one of which is shown, is connected sothat the web of primary shoe 2 pivots in one end of the links "by meansof pin 43,. and the other end of said links" pivots in the crank arm 40by means of pin 44. The from the actuating means 9 is applied. to thelinks 42 by a pin l4 which pivots atthe center. The purpose of thisadditional link 42 is to cause both shoes 2 and 3 to content the drum I,even if the shoes do not have the 'same linin drum clearance. Theoperation of this embodiment of the invention is the same as previouslydescribed except the equalizing pressure is now applied through theadded adjustment equalizing link 42.

It will be seen that the link 84 of Fig. 7 merely serves to transmit theforce of pin II to pin- 24 and for some conditions it may be desirableto make the link 84 an adjustable connecting arm. Such an arrangement isshown in Fig. 8 in which the clevis 85 is attached to link 44 at one endby means of pin it and at the other end to shoe 3 by means of pin 24.The clevis 45 has threaded ends 48-46 adapted to be engaged by lock nuts45-45 whereby the linkage system may be adjusted. The operation of thelinkage system may be aided by an added spring 48 connecting'the upperend of link 40 and the brake shoe 3. To aid in the accurate operation ofthe secondary shoe 3 it may be found desirable to add an eccentric shoeanchor 41 near the heel of the shoe. The principle of operation of thisform of the invention is identical with that disclosedin Fig. 6.

The various embodiments of my invention hereinbefore described andillustrated in the accompanying drawings constitute certain preferredforms of said invention; but I wish it to be understood that I do notdesire to be limited to the actual structural details and assembliesshown and described,for obvious modifications thereto will occur to oneskilled in the art.

Having described my invention, what I claim as new and wish to secure byLetters Patent is:

1. In a brake, a drum, a backing plate, a primary shoe, a secondaryshoe, actuating means to force said shoes into contact with saiddrum, ananchor for said primary shoe placed adjacent the end remote from saidactuating means, an anchor for said secondary shoe placed adjacent theend closest to said actuating means, and means connecting the ends ofsaid shoes remote from said actuating means, whereby the braking eii'ectof said shoes is substantially equalized, said last mentioned meansincluding a link pivoted intermediate its ends to said backing plate. 2.In a brake, a drum, a backing plate, a primary shoe, a secondary shoe,actuating means to force said shoes into contact with said drum, meansto anchor said primary shoe adjacent the end remote from said actuatingmeans, means to anchor said secondary shoe to said actuating means, andmeans connecting the ends of said shoes remote from said actuatingmeans. whereby the braking effect of said shoes is substantiallyequalized, said last mentioned means including a link centrally pivotedintermediate its ends to said backing plate.

3. In a brake, a drum, a backing plate, a pri-,

shoe, said anchoring means including a pin attached to said backingplate and-adapted to engage said primary shoe adjacent said heel, meansto anchor the heel or said secondary shoe ad- 'jacent said actuatingmeans, and means connecting the heel of said primary shoe and the toe ofsaid secondary shoe, whereby-the braking efiect of said shoes issubstantially equalized, said last mentioned means including a linkadapted to pivot intermediate its ends about a pin attached to saidbacking plate.

4. In a brake, a drum, a backing plate, a primary shoe, a secondaryshoe, said shoes each having a toe and a heel, actuating means adaptedto force said shoes into contact with said drum,

' means to anchor said primary shoe to said backhaving an operating armadapted to force said shoes into contact with said drum, means to anchorthe end of said primaryshoe remote from said actuating means to saidbacking plate, means to anchor said secondary shoe adjacent the endclosest to said actuating means, and means connecting the unanchoredends of said shoes, whereby the forces applying said shoesinto effect ofsaid shoes is substantially equalized, said to anchor said secondaryshoe adjacent said actuating means and means connecting the heel of saidprimary shoe to the toe of said secondary shoe, whereby the heel of saidprimary shoe efiectively presses the toe of said secondary shoe intocontact with said drum when said actuating force is applied, said lastmentioned means including an actuating link pivoted intermediate itsends about a pin attached to said backingplate.

6. In a brake, a drum, a backing plate, a primary shoe, a secondaryshoe, actuating means adapted to force said shoes into contact with saiddrum, an anchor for the end of said primary shoe remote from saidactuating means attached to said backing plate, an anchor for saidsecondary shoe placed adjacent the end closest to said actuating means,and means connecting the unanchored ends of said shoes, whereby theforces applying said shoes into' contact against said drum areequalized, said last mentioned means including an actuating link pivotedintermediate its ends about an anchor pin attached to said backingplate.

'7. In a brake, a drum, a backing plate, a primary shoe, a secondaryshoe, actuating means adapted to .force said shoes into contact withsaiddrum, an anchor for the end of said primary shoe remote from saidactuating means attached to said backing plate, an anchor for saidsecondary shoe attached to said actuating means, and means connectingthe unanchored ends of said shoes, whereby-the forces applying saidshoes into contact against said drum are substantially equalized, saidlast mentioned means including an actuating link pivoted intermediateits ends about an anchor pin 'attached to said backing plate.

8. In a brake, a drum, a backing plate, a'primary shoe, a secondaryshoe, actuating means contact against said drum are equalized, said lastmentioned means including a linked system having a first link pivotedintermediate-its ends, one end of said first link being connected to thefree end of said primary shoe and its other end being connected to oneend of a second link, said second link being pivoted intermediate itsends, the other end of said second link being adapted to force saidsecondary shoe into contact with said drum when said actuating means'isactuated.

9. In a brake, a drum, a backing plate, a primary shoe, a secondaryshoe, actuating means having an operating arm adapted to force saidshoes into contact with said drum, means to anchor the end of saidprimary shoe remote from said actuating means to said backing plate,means to anchor said secondary shoe to said actuating means, and meansconnectin the unanchored ends of said shoes, whereby the forces applyingsaid shoes into contact against said drum are equalized, said lastmentioned means including a linked system having a first link pivotedintermediate its ends on said operating arm, one end of said first linkbeing connected to the free end of said primary shoe, the other end ofsaid first link being connected to one end of a second link, said secondlink being pivoted intermediate its ends about a, pin attached to saidbacking plate, the other end of said second link being attached to oneend of a third link, said third link being pivoted intermediate its endsabout a pin at.- tached to said backing plate, and the other end beingadapted to force said secondary shoe into contact with said drum whensaid actuating means is energized.

10. In a brake, a drum, a backing plate, a primary shoe, 9. second shoe,actuating means having an operating arm adapted to force said shoes intocontact with said drum, means to anchor the end of said primary shoeremote from said actuating means to said backing plate, means to anchorsaid secondary shoe to said actuating means, and means connecting thunanchored ends of saidshoes, whereby the forces applying said shoesinto contact against said drum are equalized, said last mentioned meansincluding a linked system having a first link pivoted intermediate itsends on said operating am, one end of said first link being connected tothe free end of said primary shoe, the other end of said first linkbeing connected to one end of a second link, said second link beingpivoted intermediate its ends about a pin attached to said backingplate, the other end of said second link being attached to one end of anadjustable connecting member, the other end of said adjustableconnecting member being adapted to force said secondary shoe intocontact with said drum when said actuating means is energized.

. I JAMES J. CARNES.

